We have treated 3 patients with refractory and/or treatment related leukemia and 10 patients with solid tumors, of whom 5 had CNS tumors. Among the leukemia patients, no grade 3 or 4 toxicity was observed and a fleeting one log reduction in peripheral blast count was found in one patient. The maximal dose received was 3x106 cells/kg/day x 5 in leukemia patients. An intrapatient dose-escalation design allowed us to reach the maximal planned dose of 1x108 cells/kg/day x 5 days in the last 4 of the 10 solid tumor patients. Two patients had grade 2 or 3 somnolence that was self-limited and may have been related to the TALL-104 cells. One patient developed fever and rigors. These evolved concurrently with bacteremias and were associated with substantial elevations of endogenous cytokines. Neutropenia and thrombocytopenia originally attributed to TALL-104 cells in one patient were, in retrospect, probably a manifestation of labile counts since a double stem cell transplant 4 months before. This patient showed a minor response on MRI scan which lasted about 2 months. A second patient was thought to have platelets fall to 55,000/mm3 but this turned out to be an artifact as there were normal numbers of clumped platelets on smear. Three patients with CNS tumors experienced grade 2 somnolence.